It was the only remaining sticking point following months of talks between the commission and the San Diego Unified Port District, which oversees development on the public tidelands.

At the request of the commission late in the hearing, the city agreed to find $500,000 in the $520 million budget to go toward improving access to the rooftop park, but no specifics were offered on what those improvements would be.

In the last few weeks, commission staff acknowledged that the port already had made a number of concessions to reduce the project’s impacts on views to the water and public access to the shoreline.

Key among them was trimming the southwest corner of the expansion by more than 5,100 square feet on each of the project’s four levels to maintain a view down Park Boulevard to the bay. The port also committed to opening a now closed recreational pier at the foot of Convention Way, adding signage guiding people to the waterfront, and constructing a 1,900-square-foot public plaza to serve as a transition from the convention center to the Embarcadero Marina Park South.

Notable for their support Thursday of the expansion were union leaders who a year earlier had opposed the project. Organized labor, however, dropped its opposition after securing a labor agreement with the project’s construction contractor that is designed to ensure union-level wages and benefits for all workers.

State Assemblywoman Lorena Gonzalez, who at the time headed the San Diego and Imperial Counties Labor Council, said the expansion represents a reversal from years past when San Diego “took advantage of the tourism workers.”

She added, “But now we have a construction phase with local hires, training for the workers, living wages, and expansion of a hotel that pays the best of any hotels downtown. This is unprecedented in a city like San Diego.”

Besides adding more exhibition and ballroom space to the 2.6 million-square-foot center, the project will also expand the existing Hilton San Diego Bayfront by constructing a 500-room tower located to the north of the hotel. The 30-year bond financing plan for the expansion relies on about $35 million a year from the hotel tax, $3.5 million a year from the city and $3 million annually for 20 years from the Port District.

With the project now ready to move forward, questions linger about a competing project from the San Diego Chargers, who had opposed the city project and instead proposed incorporating convention facilities into a new stadium six blocks away in downtown’s East Village.

Chargers Special Counsel Mark Fabiani remained unyielding following the vote.

“The result is no surprise, given the influence of the powerful groups supporting the project,” he said in a statement. “Still, it was disappointing to see the Coastal Commission ignore its own staff’s recommendation, and now attention will turn to an appeals court ruling on the legally dubious tax that was invented to pay for all of this.”

City leaders, while welcoming a new stadium proposal, have argued all along that the expansion had to be contiguous to the existing center to meet the needs of conventioneers who don’t want to walk to a more distant location.